In an environment where sterility and biological cleanliness are required, such as various clinical medicines, food factories, medicine manufacturing plants, and basic research setting, the number of microorganisms in the air (airborne bacteria) (viable bacterial number), falling bacteria, adhesive bacteria, and the like are counted. As a method of measuring airborne bacteria, an airborne bacteria sampler for collecting floating bacteria by natural fall of floating bacteria and by suctioning a certain amount of air are generally utilized to collect the floating bacteria.
In the above methods, floating bacteria are collected on a nutrient agar plate medium, cultured in an incubator for two to three days, and a number of colonies generated after the culture is counted as the number of viable bacteria. However, this method has a disadvantage that a long time is required to culture viable bacteria.
Meanwhile, as a method capable of measuring the number of microorganisms within a short time, there has been known a method of measuring ATP (Adenosine Triphosphate) being an intracellular component by a bioluminescence method and converting the measurement result to the number of microorganisms.
In the bioluminescence method, a luciferin-luciferase luminescence reaction is used, in which the ATP amount is calculated from the luminescence amount of light generated by mixing and reacting a luminescence reagent containing substrate luciferin and enzyme luciferase and a sample solution containing the ATP extracted from a cell of a microorganism, and the number of viable bacteria is calculated based on the ATP amount per a viable bacterium. The Patent Literature 1 discloses a kit used for measuring the number of viable bacteria using such a luminescence reaction.
In the method of measuring the number of viable bacteria using the kit disclosed in the Patent Literature 1, it is possible to achieve the assured effect in terms of reduction of measurement time. However, when ultra minute amount of viable bacteria is to be measured, a luminescence amount itself is minute. Therefore, there is a disadvantage of great influence of background luminescence caused by residual ATP, intrusion of ATP not to be measured, and the like, and thus good measurement accuracy cannot be obtained.
Meanwhile, Patent Literature 2 discloses a luminescence measurement apparatus which suppresses viable bacteria adhered to a nozzle for dispensing a reagent and the background luminescence derived from residual ATP and can perform luminescence measurement accurately and promptly.
According to the luminescence measurement apparatus disclosed in the Patent Literature 2, it is considered possible to perform luminescence measurement accurately and promptly even for luminescence measurement where ultra minute amount of viable bacteria is measured.
In association with the collection of floating bacteria, Patent Literature 3 discloses a collection unit which can perform the operation of collecting and testing microorganisms floating in the air easily and within a short time.